Sixteen years of fieldwork, R&D, and innovation in computer control interface design con vince the authors that action is needed to help individuals with severe physical disabilities benefit from rapid advances in access technologies. This project develops and validates a hierarchical model of developmental skills required to use advanced single-switch interfaces to control computers and similar devices with proficiency and competence, accompanied by matrices of assessments, interventions, and hardware/software useful for diagnosis and instruction at each skill level. The Beyond Cause and Effect hierarchy and prototype materials will be reviewed in draft and final forms by a national panel of experts in single- switch applications and demonstrated in the field. Given evidence of scientific and technical feasibility in Phase I, this hierarchy will guide Phase II instructional design to produce a curriculum for teachers emphasizing clear concise training strategies to assess students' level of functioning and promote single-switch skill development beyond cause- and-effect and simple scanning toward more powerful, abstract, multifunction access technologies; a Parents' Guide for Single-Switch Skill Development and Internet site; and a technical handbook, software, and toolkit for rehabilitation professionals who work with clients using switch technology for environmental control, computer access, and communication. PROPOSED COMMERCIAL APPLICATION: Fully developed in Phase II, the Life Beyond Cause and Effect Developmental Single-Switch Skill Hierarchy, along with software, manuals, training strategies, and teaching materials will be widely used by classroom teachers, early intervention specialists, rehabilitation professionals, speech/language pathologists, and physical and occupational therapists seeking to facilitate computer access and cognitive skill development of children and adults with congenital or acquired disabilities. These materials and methods will also benefit parents and children in homes with access to inexpensive computers and mass information utilities such as AmericaOnLine. These products will be marketed nationally through an existing distributor network.